Vegetation Primary Regulator of Infiltration

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Vegetation Primary Regulator of Infiltration

• Vegetations Role Case Histories
• by
• Fred Marinelli, PhD, P.E.
• Barry Carlson, P.E.

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• Case Histories Heap Infiltration
• MAR (mean annual rainfall)
• Modeling Infiltration
• Soil Hydraulics
• Vegetation
• Coupling Both
• Long Term Vegetation Perspectives

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Case Histories

• SOURCES
• Telestos Corporate Experience
• Other Mine Sites
• NDEP

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Mean4.7
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Case History Additional Data Needs

• Inspection of Collection Systems
• Growth Medium Thickness
• Heap Orientation (aspect ,Slope)
• Vegetation Density/Diversity
• Status of Residual Drainage
• Other

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Modeling

• Various Models for Soil Hydraulics
• Some Models Can Incorporate Vegetation (ET)
• Few Incorporate Root Biomass Variation w/depth
• ?One incorporates salt build-up over time and
  respective salt tolerances of various species
• Perspective Maintain our soil hydraulic
  modeling, increase vegetation aspects
  development overtime

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Varying biomass - spacially
Evaluating Root Biomass
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Root Biomass
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5.2 MAR
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Salt Tolerance

• Salt from Atmosphere (rain,dust,etc)
• Potential salt development natural breakdown
• Potential for salt migration upward (diffusion,
  capillary)

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Leaching Requirement

• Rangeland Species
• Rangeland Environment
• LR ECw / (5ECe-ECw)
• LR Leaching Requirement
• ECw electrical conductivity applied water
• ECe average soil salinity tolerated by plant on
  a soil saturation extract

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Long Term Perspectives

• Balance within natural system leaching
  requirement
• Time frame for salt tolerance and balance to
  become evident
• Reference areas provide valuable but perhaps not
  complete comparison

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Summary

• Vegetation primary control of infiltration long
  term
• Infiltration modeling and predictions need to
  consider potential for leaching requirement -
  Balanced Vegetation (ET)
• Leaching Requirement needs to be better defined
  and understood, and incorporated into closure,
  both in time frame and extent
• Plan for ultimate cover sustainability and heap
  drainage rate (variation) long term

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Summary (Cont.)

• Heap leach cover designs should provide for some
  deep percolation, (greater than zero)
• Understand vegetation root biomass, potential
  salt loadings, and salt tolerances
• Vegetation is the Controlling Factor long term

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• THANK YOU!